xiii THE DECOMPOSITION OF THE ALKALIS 267 



present in the amalgam (which contained two volumes of 

 ammonia in combination with one volume of hydrogen) was 

 composed of one volume of nitrogen united to four volumes 

 of hydrogen. 



Davy (1808) suggests the name "Ammonium." In 

 suggesting the name AMMONIUM for the substance present 

 in the amalgam Davy writes : 



"The more the properties of the amalgam obtained 

 from ammonia are considered, the more extraordinary do 

 they appear. 



" Mercury by combination with about TWOO^ P art f lts 

 weight of new matter, is rendered a solid, yet has its specific 

 gravity diminished from 13*5 to less than 3, and it retains 

 all its metallic characters; its colour, lustre, opacity, and 

 conducting power remain unimpaired. 



"It is scarcely possible to conceive that a substance 

 which forms with mercury so perfect an amalgam, should 

 not be metallic in its own nature ; and on this idea to assist 

 the discussion concerning it, it may be conveniently termed 

 ammonium" (Works, V. 130-131). 



Ampere (1816) and Berzelius (1823) on the ammonium 

 radical. The discovery of ammonium amalgam had the 

 effect of emphasising the close analogy of the compounds of 

 ammonia with those of the alkali metals. Ampere in 1816 

 pointed out that the salts of the fixed and volatile alkalies 

 would be strictly analogous if the " ammonium " of Seebeck's 

 amalgam were regarded as the metallic base of the salts of 

 ammonia. 



" This difficulty would disappear by admitting that . . . 

 the compound of one volume of nitrogen and four volumes 

 of hydrogen, which is united to mercury in the amalgam 

 discovered by Seebeck, and to chlorine in the hydrochloride 

 of ammonia, behaves as a metal in all the compounds which 

 it forms ; in such a way that a volume of ammonia gas 

 combined with half a volume of water-vapour would be 

 considered as a sort of oxide ; with half a volume of 



